This application claims priority of a German patent application DE 100 04 661.4 filed Feb. 3, 2000 which is incorporated by reference herein.
The present invention refers to an apparatus for slewing a light beam, having a base element and a support element carrying a light source or an optical component, wherein connecting elements which allow movement of the support element relative to the base element extend between the base element and the support element.
Apparatuses of the generic type are used for positioning and aligning optical components. These apparatuses generally have a base plate which is joined to a support plate in such a way that the support plate performs a tilting movement about a central point relative to the base plate. The tilting movement of the support plate is usually brought about by way of adjusting screws located on the base plate, with which the spacing between the base plate and the support plate at the location of the respective adjusting screw can be changed. With these arrangement, optical components such as, for example, mirrors, prisms, lenses, or small laser light sources can be exactly and reproducibly positioned and aligned.
As already mentioned, however, these apparatuses tilt about a point that usually lies between the base plate and the support plate. For many applications, however, it is necessary for a light beam to be tilted or slewed about a point lying at a physically difficult-to-access location, for example in the intermediate image plane of an optical assemblage. An apparatus of this kind generally cannot be arranged at that location, so that slewing of the light beam about the intended point can be achieved, for example, with the aid of an intermediate image. An intermediate image makes it possible to displace the tilting point of the apparatus to the intended location. This entails a great deal of design complexity, is complex in terms of alignment, represents a source of additional imaging errors, and is moreover associated with losses of available light intensity.
It is therefore the object of the present invention to eliminate or at least reduce the disadvantages of the additionally used optical components.
The aforesaid object is achieved by way of the features of claim 1. According to the latter, the apparatus according to the present invention for slewing a light beam has a base element and a support element carrying a light source or an optical component, wherein connecting elements which allow movement of the support element relative to the base element extend between the base element and the support element. The apparatus for slewing the light beam is characterized in that the connecting elements are spaced apart differently at their ends facing toward the base element and their ends facing toward the support element, or at the connecting points at the two ends.
What has been recognized firstly according to the present invention is that the light beam can be slewed surprisingly easily about the mechanically difficult-to-access point if the tilting point of the apparatus itself can be displaced to that location. The advantageous result is that the additional optics for intermediate imaging become superfluous, and the alignment problems of those optical components, as well as their imaging errors, are thus effectively eliminated. In addition, in particularly advantageous fashion, the decrease in the number of components means that the entire assemblage can be made smaller, manufacturing costs are reduced, and the optical beam path is (considerably, in some cases) simplified.
The slewing point of the apparatus is displaced to the intended location by the fact that the apparatus has connecting elements which extend between the base element and the support element. These connecting elements allow a relative movement between the support element and base element that is defined by the geometrical or three-dimensional arrangement of the connecting elements. According to the present invention, the connecting elements are spaced apart differently at their ends facing toward the base element and their ends facing toward the support element, or at the connecting points at the two ends. Two connecting elements and the lines between their connecting points at the two ends thus describe a trapezoid. When a relative movement of the support element occurs with respect to the base element, the guidance system of the connecting elements causes the support element to be guided on a predefined three-dimensional curve. Because of the trapezoidal arrangement of the connecting elements, when the support element moves, the latter is deflected along its movement direction; in particular, it is additionally tilted relative to the base element. As a result of the combination of these two forms of movement (deflection and tilting), the desired slewing movement of the support element about a point spaced away from the apparatus is achieved in a manner according to the present invention. An optical component or light source carried by the support element is constrained to perform this slewing movement, so that the light beam also slews about the point spaced away from the apparatus.
The base element is joined in stationary fashion to the housing of the optical beam path. A relative movement between support element and base element thus means a relative movement between the support element and the housing of the optical beam path. A stationary arrangement of the base element on an optical stage (breadboard) would also be conceivable.
Advantageously, the base element and/or the support element could themselves be assembled from connecting elements, so that, for example, the connecting elements making up the support element permit a relative movement. The number of degrees of freedom of the relative movement between the support element and base element can thereby be even further increased.
If the light beam is to be slewed only in one plane about one point, two connecting elements are provided between the base element and the support element. For that purpose, the connecting elements could have correspondingly large dimensions so that any transverse movement with respect to the intended slewing movement of the support element is prevented.
In an alternative embodiment, at least three connecting elements are provided between the base element and the support element. This makes possible a defined relative movement with more degrees of freedom between the support element and base element, so that the light beam can be slewed not just in one plane about one point.
In a preferred embodiment, an even number of connecting elements is provided between the base element and the support element. If the connecting elements are correspondingly arranged, this can resulting in well-defined slewing movements of the light beam in several directions that are linearly independent of one another.
If an even number of connecting elements is provided, the ends of the connecting elements, or the connecting points, are differently spaced apart in paired fashion. This again ensures, depending on the arrangement of the connecting elements, that the support element performs a slewing movement, and not just a parallel offset, relative to the base element.
In a preferred embodiment, the spacings of the ends of the connecting elements (or their connecting points) facing toward the base element are smaller than those of the ends of the connecting elements (or their connecting points) associated with the support element. A light beam that extends from the support element in the direction of the base element and passes through the base element is thus slewed, upon deflection of the support element, about a point that is located, when viewed from the support element, beyond the base element. This embodiment is particularly advantageous for use in microscopy, since by appropriate dimensioning of the apparatus according to the present invention, the point about which the light beam is slewed can be placed in an intermediate image plane of the optical beam path.
If the spacing relationships are reversedxe2x80x94i.e. the spacings of the ends of the connecting elements (or their connecting points) facing toward the base element are greater than those of the ends of the connecting elements (or their connecting points) facing toward the support elementxe2x80x94then a light beam extending from the support element in the direction of the base element is slewed about a virtual point that is located, when viewed from the base element, beyond the support element. This embodiment could be advantageous for projection devices, since the slewed light beam diverges in the projection direction.
The connecting elements could be of rigid configuration in order to ensure a reproducible slewing movement of the support element.
The term xe2x80x9cconnecting pointsxe2x80x9d will be used hereinafter to refer to the ends of a connecting element; a connecting point can be provided between a connecting element and the support element, or between a connecting element and the base element, or between two connecting elements.
The connecting points of the connecting elements could advantageously be configured as ball joints. This would allow a connecting element to move relative to the base element or the support element in directions that are linearly independent of one another.
The connecting points could furthermore be configured as axis joints, universal joints, fork joints, or flexural elements. A combination of different connecting points for the connecting elements used in an apparatus is also conceivable. By appropriately selecting the type of connecting point, it is thus possible to define the relative movement of the support element with respect to the base element.
In a concrete embodiment, the base element has at least one guide element by way of which the support element is guided during movement. The guide element could, in this context, be configured as a parallelepipedal component, for example a plate, which projects from the base element and is directly in guiding contact with the support element. In order to stabilize the guidance system during a relative movement of the support element, the guide element could have a longitudinal groove into which a corresponding countermember, provided on the support element, engages. In addition, the guide element could have a longitudinal hole, corresponding to the relative movement of the support element, into and through which a corresponding countermember provided on the support element projects and engages behind the guide element.
In a particularly advantageous embodiment, the support element, the base element, and the connecting elements are fabricated from one integral piece. Production of this integral piece could be accomplished by either material-removing or non-material-removing shaping. The process of manufacturing an apparatus of this kind could thus be largely simplified or automated, so that time-consuming assembly of the (in some cases small) individual parts is not necessary.
At least one adjusting element which brings about the relative movement between the base element and the support element is provided on the support element and/or on the connecting element. If the support element is to perform a movement along only one direction, one adjusting element is provided. This adjusting element acts along that one direction. If the support element is to perform a movement in directions linearly independent of one another, at least two adjusting elements are provided for that purpose, each acting in one of the respective adjustment directions.
The adjusting element could act either between the base element and the support element or between an external component and the support element. The external component could be, for example, the housing receiving the optical beam path, so that the adjusting element ultimately acts between the housing and the support element.
The adjusting element is embodied as a screw with preferably a shallow pitch, or as a micrometer screw. A micrometer screw with a differential mechanism could also be used. In this context, the external component or the support element or the base element could have corresponding threads into which the micrometer screw is threaded. To perform the relative movement between the support element and the base element, the spacing between the base element and the support element can be correspondingly set by actuating the screw. The adjusting elements embodied in this fashion are preferably used to align a light source or an optical component that is carried by the support element.
For dynamic movement of the support element, for example in order to scan a light beam with the apparatus according to the present invention, the adjusting element is arranged movably with respect to the support element or the connecting element. The connecting point between the adjusting element and the support element or the connecting element could, in this context, be embodied as a ball joint, axis joint, universal joint, fork joint, or flexural element. The adjusting element could be configured as a rigid or flexible component, and could be connected to a drive unit.
A stepping motor or a direct-current motor could be used as the drive unit. Alternatively, a galvanometer could be used as the drive unit. This is advantageous in particular if an alternating movement of the support element needs to be achieved.
By way of the selection of the geometry of the support element and the base element and the arrangement of the connecting elements, the light beam slews substantially about a point which has a spacing from the support element that is defined, for small angular deflections, by the formula R≈HT/(Txe2x88x92B), where H is the spacing between the base element and the support element in the zero position, B is the spacing of the ends of the connecting elements facing toward the base element, and T is the spacing of the ends of the connecting elements facing toward the support element. The apparatus for slewing a light beam can thus be configured and produced for a concrete application, and in consideration of the space available in a device.
In a concrete embodiment, the apparatus for slewing a light beam is fabricated from one integral piece. The base element and the support element are embodied as a parallelepipedal plate, and the connecting elements as narrow struts with a square cross section. The struts are joined at the connecting points to the support element or to the base element via a reduction in material, so that the connecting elements act as flexural elements in the reduced-material region.
The base element has a parallelepipedal guide element that projects from the base plate toward the support element and extends almost as far as the support element. Two adjusting elements, which act substantially perpendicular to one another and act between the support element and the parallelepipedal guide element of the base element, are provided for the relative movement of the support element with respect to the base element. The base element, the support element, and the guide element have an opening through which the light beam can pass. The optical component, preferably a laser, is mounted directly onto the support element. Advantageously, a coupling-out optical system (plus attachment mechanism) of a glass fiber could also be mounted on the support element. The light beam emitted from the laser or glass fiber passes through the openings in the support element, parallelepipedal guide element, and base element. The use of a glass fiber to transport the laser light makes it possible to dispense with the installation of a laser on the support element. In particular, only the coupling-out optical system of the glass fiber then needs to be moved by the apparatus, and not the complete laser.